1. Field of the Invention
This invention relates to a pad bearing, in other words, a centering block, which is a slide bearing for a one-way clutch employed for operations such as torque transmission, backing-off and overrunning in an automatic transmission for an automotive vehicle, and especially to a centering block capable of guiding a lubricating oil to clutch members such as sprags or rollers.
2. Description of the Related Art
A conventional one-way clutch is illustrated in FIG. 12 through FIG. 16, in which FIG. 12 is a simplified schematic front view of the conventional one-way clutch, FIG. 13 is an enlarged fragmentary front view of the conventional one-way clutch, FIG. 14 is a front view of a centering block in the conventional one-way clutch, FIG. 15 is a fragmentary front view of a cage in the conventional one-way clutch, and FIG. 16 is a plan view of bent pieces of the cage in the conventional one-way clutch as viewed in the direction of arrow A in FIG. 15.
In FIG. 13, the conventional one-way clutch comprises an inner member 30 and an outer ring 1. Arranged between the inner member 30 and the outer ring 1 are rollers 2. Cam surfaces 1a are formed on an inner peripheral wall of the outer ring 1, whereby a cam mechanism is constructed of the rollers 2 and the corresponding cam surfaces 1a to allow the inner member 30 to rotate only in one direction relative to the outer ring 1. Namely, the inner member 30 is allowed to idle in a direction indicated by arrow B in FIG. 13 relative to the outer ring 1. On one side of the outer ring 1, a cage 3 is arranged coaxially with the outer ring 1. The cage 3 covers one end faces of the individual rollers 2. Parts of the cage 3 are bent to form bent pieces 3a, which extend between the inner member 30 and the outer ring 1. Tips 3b of the bent pieces 3a project out beyond an opposite side of the outer ring 1. On the opposite side of the outer ring 1, a side plate 4 is disposed covering opposite end faces of the rollers 2. The side plate 4 defines small holes 4a, through which the bent pieces 3a of the cage 3 extend. The tips 3b are crimped on an outer surface of the side plate 4 so that the side plate 4 is disposed coaxially with the outer ring 1 and the inner member 30 and the cage 3 and the side plate 4 are fixed on the outer ring 1.
Between the outer ring 1 and the inner member 30, centering blocks 5 are disposed. Each centering block 5 is composed of a sliding portion 5a, bent portions 5b, and support portions 5c connecting the sliding portion 5a and the individual bent portions 5b, respectively. The sliding portion 5a is maintained in sliding contact with the inner member 30, while the bent portions 5b are maintained in engagement with a corresponding recess 1b formed in an inner peripheral wall of the outer ring 1 and supported by the corresponding bent pieces 3a. The centering block 5 is hence fixed in the corresponding recess 1b of the outer ring 1 with the bent portions 5b being supported on the corresponding bent pieces 3a. The cage 3 is provided with L-shaped spring brackets 11 supporting thereon springs 10, respectively. Each spring 10 urges the associated roller 2 against the corresponding cam surface 1a. The bent pieces 3a also serve as stoppers for preventing rotation of the cage 3 against urging forces of the springs 10. Each support portion 5c is provided with a lubricating oil hole 5d through which a lubricating oil is allowed to flow.
Although not shown in the drawings, lubricating oil feed channels extend radially through the inner member 30 from its inner peripheral wall to its outer peripheral wall. The lubricating oil can therefore be fed under centrifugal force to the rollers 2 through the lubricating oil feed channels. Alternatively, the lubricating oil can be fed into a closed structure with the respective centering blocks 5 from an unillustrated lubricator and then to the rollers 2 through the lubricating oil holes 5d of the centering blocks 5.
Accordingly, the lubricating oil inside the one-way clutch can flow through the lubricating oil holes 5d, namely, can recirculate inside the one-way clutch without being blocked by the centering blocks 5.
Conventional centering blocks are however formed by pressing a metal sheet, so that they have a uniform wall thickness and an open shape. They are hence accompanied by the drawback that they are prone to deformation when subjected to a radial load and they are not resistant to vibrations applied from an associated outer ring.